Marie ClaireCarrie Underwood went from obscurity to superstardom in just a matter of months during her time on American Idol, which she won in 2005. The stress of suddenly having thousands of people all clamoring to get to her at concerts or in other public places led Carrie to suffer panic attacks early in her career.

She tells Marie Claire, "People were touching me, screaming -- it made me really nervous. In public, I just get nervous. It’s a physical reaction, feeling like the walls are closing in."

That's not to say Carrie doesn't love all the attention from her fans.

She explains, "The fans are great. It’s not their fault. I don’t ever want to come across as ungrateful. But on my end, it is hard for me to process. Because I am still just me.”

Carrie's nervous reaction to those big crowds is partly a result of her upbringing. Her older sisters were already out of the house by the time she came of age back home in Oklahoma, so Carrie was basically raised as an only child. That environment led her to treasure her solitude as an adult.

"I’m a little more selfish, a little more independent, a little closed," Carrie says. "I do wish I were softer. I wish I were able to form relationships better. But hey, I mean…I’m not a sociopath.”

To read the rest of Carrie's Marie Claire cover story, pick up the magazine's June issue hitting stands May 21.